Propargyl bromide (3-bromopropyne) is known to be useful as a soil fumigant for control of fungi, nematodes, and undesirable plant life. See for example U.S. Pat. No. 2,794,727. For such usage it would be necessary to store and transport propargyl bromide from its manufacturing site to other locations and ultimately to farmlands where it would be put to use. And, in order to utilize propargyl bromide most effectively as a soil fumigant it would be desirable to have the ability to use it in pressurized dispensing systems wherein the pressurized fumigant is injected subsurface to the soil during cultivation.
Propargyl bromide is, however, a high energy material that is sensitive to physical shock or impact, and that is also susceptible to rapid thermal decomposition upon exposure to high temperatures or fires. In order to more safely produce, purify, store, transport, handle and use propargyl bromide, it is desired to stabilize the propargyl bromide against physical shock and exposure to elevated temperatures both in the liquid and vapor phase especially when in a confined space. In addition, since use of propargyl bromide as a soil fumigant would often involve having the product housed in pressurized systems or containers so that it can be injected into the soil, stabilization of propargyl bromide against physical shock and exposure to elevated temperatures when confined under pressure is another goal to be accomplished.
The hazardous character of propargyl bromide has been recognized heretofore, and certain stabilizing materials have been proposed for use. For example, as indicated in Brit. 1,132,417, propargyl bromide is shock sensitive, and when in a confined space, propargyl bromide may ignite spontaneously and decompose with explosive violence, and may detonate. To provide stabilization, Brit. 1,132,417 indicates that certain solvents were effective, namely toluene, xylene, a non-cyclic ether, tetrahydrofuran, dioxane, beta-ionone, and ethanol. Brit. 1,132,417 further points out that many organic liquids had been tried for the purpose of stabilizing propargyl bromide, but only a few had been successful, that no firm rule had been established for predetermining which liquids would be successful and which would not, and that among materials that were tested and found ineffective were hexane, benzene, chloroform, formamide, and light petroleum oil.
In a paper entitled “Explosibility and Stabilization of Propargyl Bromide”, Loss Prevention, 1967, 1, 6–9, it is noted that propargyl bromide is sensitive to both shock and to temperature, and that under suitable conditions may be detonated, and that stabilization by dilution was explored as a possible solution to this problem. The authors of this paper report that at a diluent level of 15%, benzene, formamide, chloroform and hexane were judged by impact tests to be poor stabilizers for propargyl bromide, and that diethyl ether and diisopropyl ether appeared promising but were considered less attractive than toluene, xylene, and ethylhexylsorbitol. Based on processing considerations and impact test results, toluene and xylene were selected by the authors of this paper for further testing. In confinement tests toluene was judged by them to be the material of choice, especially at a dilution level of 20–30%. At present, propargyl bromide diluted with 20% of toluene is available as an article of commerce.
Unfortunately, toluene and xylene are both incapable of effectively stabilizing propargyl bromide in the vapor state. Thus conditions could be encountered in which propargyl bromide in admixture with toluene might nonetheless undergo explosive decomposition. Also, in order to use propargyl bromide as a soil fumigant it is important to avoid contaminating the soil with materials that leave residues that are not readily broken down by naturally-occurring microorganisms in the soil. Aromatic hydrocarbons such as toluene and xylene are not environmentally friendly as they are not rapidly consumed by such naturally-occurring microorganisms.
Thus a need exists for a new, environmentally-friendly way of effectively stabilizing propargyl bromide against both shock-induced and rapid heat-induced decomposition when in the vapor state and in the liquid state, and especially when under confinement under pressure. Because of the hazardous characteristics of propargyl bromide this need exists at all stages of its existence, including production, recovery, purification, handling, storage, transportation, and use.
Another need is for a more effective, environmentally-friendly, and less hazardous way of effecting space fumigation of enclosed spaces such as industrial and residential buildings, and especially of bulk commodities infested with or susceptible to infestation by pests, while being stored or transported in such closed spaces as bulk containers, bulk storage or transportation vessels or bins, silos, grain elevators, shipholds, bulk transport railway or road trucks warehouses, storage sheds, and the like.
This invention enables fulfillment of these and other needs as well.